Code :
HttpRequest currentRequest = HttpContext.Current.Request;
string ip = currentRequest.ServerVariables["HTTP_X_FORWARDED_FOR"];
string getip = "";
if (!string.IsNullOrEmpty(ip))
{
string[] ipRange = ip.Split(',');
getip = ipRange[0].Trim();

}
else
{
getip= Request.ServerVariables["REMOTE_ADDR"];
}
label1.text=getip;